Due to a rapid growth of a wireless mobile communication market, various multimedia services under a wireless environment are being needed, and in particular, the volume of data transmission becomes large and data is being transmitted at a high speed. Thus, a study on building, by using limited radio resources, a communication system that has high speed and reliability, such as a maximum data rate and a minimum error rate, is being conducted. In order to build the communication system that has the high speed and reliability, a new transmission technology using multiple antennas is needed and as an example, a Multiple Input Multiple Output (MIMO) system using multiple antennas is being used. The MIMO system is a system of which the transmitting and receiving ends each use multiple antennas, and an active study on that is recently conducted because the MIMO system may increase a channel transmission capacity in proportion to the number of antennas even without further frequency or transmit power assignment as compared to a single antenna system.
The multi-antenna technologies may be roughly divided into a spatial diversity scheme that enhances transmission reliability by obtaining a diversity gain corresponding to the product of the numbers of transmitting and receiving antennas, a Spatial Multiplexing (SM) scheme that increases a bit rate by simultaneously transmitting rows of signals, and a scheme that is a combination of the spatial diversity and spatial multiplexing.
The spatial diversity scheme may have a diversity effect of being proportional to the product of the number of transmitting antennas and the number of receiving antennas by using Space Time Block Coding (STBC). Thus, it is possible to enhance reception performance.
In general, since each of the spatial diversity scheme and the spatial multiplexing scheme has advantages and disadvantages, these two schemes are combined. For example, the spatial multiplexing scheme is used in a strong magnetic field so as to enhance a transmission speed and the spatial diversity is used in a weak magnetic field so as to minimize a decrease in antenna efficiency and thus, prevent a decrease in system performance.
On the other hand, a portable terminal in addition to a base station is recently using multiple antennas, and in general, it has internal antennas at its upper and lower ends. Thus, when a user attempts to make a voice call or data communication, griping his/her terminal, antennas in the portable terminal are affected by how the user grips the terminal, in addition to a channel environment. For example, when the terminal is affected by a human body, the efficiency of the antenna corresponding to a contact part decreases even in a good magnetic field state and thus, there is a drawback that the entire transmission rate decreases.
Therefore, there is a need for a method and a device for minimizing a decrease in antenna efficiency caused when an electronic device is in contact with a human body.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.